Remove #ifdef MULTIBYTE per hackers list discussion.

src/backend/commands/copy.c

src/backend/commands/dbcommands.c

src/backend/parser/analyze.c

src/backend/parser/scan.l

src/backend/postmaster/pgstat.c

src/backend/regex/engine.c

src/backend/regex/regcomp.c

src/backend/regex/regerror.c

src/backend/regex/regexec.c

src/backend/regex/regfree.c

src/backend/tcop/postgres.c

src/backend/utils/adt/ascii.c

src/backend/utils/adt/format_type.c

src/backend/utils/adt/like.c

src/backend/utils/adt/oracle_compat.c

src/backend/utils/adt/quote.c

src/backend/utils/adt/selfuncs.c

src/backend/utils/adt/varchar.c

src/backend/utils/adt/varlena.c

src/backend/utils/error/elog.c